Coil32
- Coil32 is a free coil inductance calculator, that allows to calculate: single layer and multi layer air core coils, toroidal air core coils, inductors on ferrite rings, in pot core, flat coils on the PCB, and also LC resonance parameters. The program have additional plugins to calculate another kinds of coils.
The application is free for usage and distributing.

Assessing unknown FerriteToroids
- Ok so you have had a good day at the Rally and you have come back with a carrier bag full of ferritetoroids that "just might be useful for something". How do you find out what they are? Very few seem to be stamped with any indication of their properties, and some are 'painted' garish colours which presumably means something.